The use of introducer assemblies designed to deploy implantable medical devices endoluminally is extensive in light of the many clinical and physiological advantages this provides. Such introducer devices are commonly inserted percutaneously into a patient from a location a significant distance from the site at which the device is to be implanted. For instance, aortic medical devices are often inserted through the patient's femoral artery. As a consequence, introducer assemblies have significant lengths, some well over one to one and a half meters.
Often, the introducer assembly must follow a tortuous path through the patient's vasculature, with the result that it will be curved and twisted by the time its distal end, which carries the medical device, reaches the site at which the device is to be implanted.
Moreover, in order to treat some medical conditions, the implantable medical device may itself have a substantial length. Devices having a length of 100 to 200 millimeters or more are not uncommon.
These characteristics can lead to it being necessary to impart a substantial force on the introducer assembly, particularly at the start of the deployment procedure. Moreover, in the case of a long medical device, the components of the introducer assembly need to be moved by substantial distances. For instance, the outer sheath, which covers the implantable medical device during transportation and insertion of the introducer assembly into the patient, must typically be retracted by at least the length of the medical device. This can cause difficulties at the proximal end of the introducer assembly, that is at its external handle section, in terms of the distance to be covered to retract the sheath and the consequent length of the handle section of the assembly. It is known to provide sheaths which can be split and then rolled so as to reduce the length of the handle section.
While a splittable sheath can resolve some of the disadvantages mentioned above, their structure makes it difficult to provide mechanical assistance for operating the introducer assembly, particularly due to the need to flush the assembly before use and to provide a substantially fluid sealed assembly to prevent undesired fluid loss from the patient.